1. Field
The present disclosure relates generally to lenses and, in particular, to lenses for use with antennas. Still more particularly, the present disclosure relates to a method and apparatus for steering a radio frequency beam using a negative index metamaterial lens.
2. Background
Phased array antennas have many uses. For example, phased array antennas may be used in broadcasting amplitude-modulated and frequency-modulated signals for various radio stations. As another example, phased array antennas are commonly used with seagoing vessels, such as warships. Phased array antennas allow a warship to use one radar system for surface detection and tracking, air detection and tracking, and missile uplink capabilities. Further, phased array antennas may be used to control missiles during the course of the missile's flight.
Additionally, phased array antennas are commonly used to provide communications between various vehicles. Phased array antennas also are used in communications with spacecraft. As another example, a phased array antenna may be used on a moving vehicle or seagoing vessel to communicate with an aircraft.
The elements in a phased array antenna may emit radio frequency signals to form a beam that can be steered through different angles. The beam may be emitted in a direction normal to the surface of the elements radiating the radio frequency signals. Through controlling the manner in which the signals are emitted, the direction may be changed. The changing of the direction is also referred to as steering. For example, many phased array antennas may be controlled to direct a beam at an angle of about 60 degrees from a normal direction from the arrays in the antenna. Depending on the usage, a capability to direct the beam at a higher angle, such as, for example, about 90 degrees, may be desirable.
Some currently used systems may employ a mechanically steered antenna to achieve greater angles. In other words, the antenna unit may be physically moved or tilted to increase the angle at which a beam may be steered. These mechanical systems may move the entire antenna. This type of mechanical system may involve a platform that may tilt the array in the desired direction. These types of mechanical systems, however, move the array at a rate that may be slower than desired to provide a communications link.
Therefore, it would be advantageous to have a method and apparatus to overcome the problems described above.